Process of decolorizing hydrocarbon material



Patented May 2, 1933 SUMNER E. CAMPBELL, OF LONG BEACH, CALIFORNIA PROCESS OF DECOLORIZING HYDROGARBON MATERIAL Application filed July 16,

This invention relates to a process for treating hydrocarbon material wherein products having valuable properties are recovered.

The principal object of the invention is to recover the acidic and basic impurities held by chemical combination or in solution in the exhausted alkali and acid used in the treatment of petroleum distillates, and to apply such mixtures to the treatment of ores as frothing agents in the so-called flotation process.

One particular process of treating petroleum distillates and recovering such mixtures is set forth and claimed {in my copending application, Serial No. 349,606, filed March 25, 1929, and a second process is set forth and claimed in my copending application Serial No.357,710, filed April 24, 1929, of which this application is a continuation in part.

The exhausted acid, or alkali, from both said methods may be used as frothing agents in flotation processes, and for illustrative purposes, a process of treating petroleum distillates will be described in which, by reference to the diagrammatic sheet of drawing, it will be seen that raw distillate is continuously supplied through a pipe and valve 26 to a treatment chamber, or tower, 11, which is the first of a plurality of such chambers 11, 11, 11', and 11'.

Depending on the distillate undergoing treatment, said chambers are partly filled with an acid, preferably sulphuric acid, which in certain cases may be weak sulphuric acid of about 50% strengthand in other cases may be strong sulphuric acid of 40 66 Baum gravity containing about 93.19%

For convenience, the process of treating gasoline to decolorize the same with weak sulphuric acid containing less than 93.19%

5 H SO and alkali, as set forth in said copending application Serial No. 349,606, will be described although it must be understood that the exhausted strong acid and alkali recovered by the process set forth in said 50 co-pending application Serial Number 357,-

710 are also valuable as frothing agents and 1929. Serial No. 378,710.

are included herein in the products claimed.

Referring now again to the towers 11, 11, 11, and 11, it "will be'understood that, inasmuch as all the towers are of like construction and produce like effects in succession, the description and function of one tower are applicable to all.

Tower 11 is filled with anysuitable inert acid resistant material 12 to give large surfacercontact of gasoline with acid, and is partly filled to the line X- X with sulphuric acid of about strength, introduced through the pipe 13.

The gasoline is intimately contacted with the acid by bubbling therethrough and passes successively through valve 27, pipe 14., valve 28, tower 11, valve 27, pipe 14', valve 28, tower 11", valve 27", pipe 14", valve 28", tower 11", valve 27", to a pipe 15, by which it is conveyed to alkali towers through a valve 34 for further treatment with caustic soda, as will be presently described, valves 26, 26", 26', 29, 29, 29", 29, 30, 30 80", 30, 31, 31, 31", and 33 being closed.

In this manner a continuous stream of gasoline is contacted with successive relatively small portions of weak acid, the first of which is first partially spent, or exhausted, by reaction with the basic compounds, and the last of which is substantially fresh so that, by thus successively contacting, the removal of compounds of abasic nature by reaction is assured, with no resulting waste of unrecoverable acid.

In the. course of such treatments the weak acid in the first tower 11, by reaction with basic compounds, will become substantially completely used up, or exhausted, whereupon valves 26, 27, and 28 are closed and valve 26' is opened to prevent the passage of gasoline through tower 11, whereafter valve 29 is opened to drain tower 11 of the exhausted acid together with the basic impurities it has combined with or absorbed, 95 such, for example, as nitrogenous bases, into a manifold 38 whichconveys the same to a storage tank 39 for further desired treatment or use as a frothing agent.

As soon as the substantially exhausted acid is withdrawn from the first tower 11, valve 29 is closed and valve 37 opened to fill tower 11 with fresh weak acid through pipe 13 to the level X--X, after which valve 37 is closed and tower 11 becomes ready for use as the last of the series instead of the first.

Pipe 15 is divided at a valve 34 to maintain the plurality of towers in operation in rotation, which is accomplished after the withdrawal of exhausted acid from the first tower 11, and the replenishing thereof with fresh weak acid, by closing valve 34 and opening a valve 33 in a bypass manifold pipe 32 adapted to selectively and in rotation pass the gasoline through the plurality of towers by means of suitable pipes 36, 36', 36", and 36" controlled by valves 30, 30, 30", and 30', respectively.

At the same time that by-pass manifold 32 is opened, a withdrawal by-pass manifold 35, connected to suitable extensions of pipes 14, 14, and 14", through valves 31, 31 and 31 respectively, will be opened through one or the other of said valves to maintain the flow of the acid treated gasoline back to pipe 15 and further alkali treatment.

Referring back to first tower 11, which had just been recharged with fresh weak acid, valve 34 is now closed and valves 33, 30, 27 and 31 are opened, whereby the gasoline from tower 11" passes back through tower 11 and thence through pipe 14 and manifold 35 to pipe'15,-tower 11 becoming the first of the series and tower 11 the last.

Upon further continuous operation and upon exhaustion of the acid in tower 11, valves 26, 27', and 28' are closed and valve 26" is opened, to the end that tower 11 is drained and recharged, by manipulation of the proper valves, with fresh weak acid as already described, whereupon valve 31 is closed and valves 28, 27 and 31 are opened, to thus make tower 11" the first of the series and tower 11 the last of the series.

In like manner, any number of weak acid towers can be operated in rotation in order that the greatest efliciency may be obtained from the smallest possible amount of acid employed, substantially no free acid being drawn off from the respective towers to the mixture in storage 39.

This is a great contrast to the usual acid treatments for decolorizing where in the neighborhood of 80% of free acid is often withdrawn in the acid sludge. 1

In order that no acid may be carried over to the caustic soda towers, which are used in the next step of my process, pipe 15 carries the acid treated gasoline to a settling chamber 16, whence any acid may be withdrawn through a pipe 17; but any acid trapped therein is very small inasmuch as the rate of throughput is such as to prevent any material amount of acid leaving the last of the series of acid towers.

The gasoline now passes through pipe 18 and valve 40 to a tower 19, which is constructed in like manner to acid tower l2, and is partially filled with an alkaline solution, for example a solution of caustic soda, to the level of YY.

In using a relatively strong solution of caustic soda in tower 19, for instance a solu tion containing 30% of sodium hydroxide, I have found that such solution absorbs the acidic impurities in the acid treated gasoline with avidity, to the'end that the solution absorbs about an equal volume of acidic impurities, or more, depending on the nature of the hydrocarbon material treated, before becoming exhausted.

While I do not limit myself to the use of a 30% solution of sodium hydroxide, or equivalent solutions like potassium hydroxide or sodium plumbite, as stronger or weakor solutions may be used, it is advantageous to do so as the chemical treatment of the gasoline may be ended by one passage through such strong solution whereby the maximum amount of acidic impurities may be concentrated therein in comparatively small volume.

For the same reason the renewal of the sodium hydroxide in tower 19 will be less frequent.

However, for convenience, I provide for the use of two or more towers 19 and 19' in series, primarily to maintain continuous operation, and secondly in case a plurality of towers is necessary when weak caustic soda solutions are used. In the latter case, a plurality of caustic soda towers can be arranged for use in rotation, as already described for the weak acid towers.

Valve 43 is closed and the gasoline is bubbled through the caustic soda solution in tower 19 and passes out through valve 41, pipe 32, and valve 40 to a second caustic soda tower 19, thence through valve 41 and pipe 42 to a settling tank 22, wherein any caustic soda solution carried over is settled out and withdrawn through pipe 43, and the treated gasoline then passes through a filter 24 to storage, or use, by means of a pipe 25.

The treatment in towers 19 and 19' insures the removal of acidic impurities in the acid treated gasoline, as well as the neutralization of any free acid carried therein, and after a predetermined period of operation the caustic soda solution in tower 19 becomes exhausted, due to reaction with such acidic compounds and any free acid.

Upon exhaustion of the caustic soda solution in tower 19, valves 40 and 41 are closed and valve 43 opened, to the end that the treatment continues in tower 19, which thus becomes the first of a desired series instead of the last.

Valve 44 is then opened and the exhausted caustic soda solution and reaction products from tower 19 are drained through a pipe 45 to a storage tank 46, wherein they may be held for further treatment elsewhere for the recovery of valuable acidic materials and withdrawn through pipe 47 or used as a frothing agent.

Valve 44 is then closed and valve 48 opened to partially fill tower 19 with fresh caustic solution supplied by a feed pipe 20, after which valve 48 is closed.

Tower 19 is thus charged and ready for further operation upon exhaustion of tower 19, when valves 43, 40 and 41 will be closed, and valves 40, 41, and a valve 49 in a bypass line 50 will be opened.

Or, as already stated, a plurality of canstic soda towers can be arranged in series as provided for the weak acid towers.

By the above described continuous treating operation, it will be seen that decolorization of distillates may be effected selectively, first in removing impurities of a basic nature which may be recovered as valuable by-products, and then removing impurities of an acid nature which may be recovered as valuable by-products, the removal of both classes of impurities being accomplished by the use of minimum quantities of acid and alkali, which are used to exhaustion.

In addition, after said treatments, there may still be in the gasoline certain chromogenic and other bodies unaffected by such treatments, which cause the gasoline to appear turbid and lack brilliancy, and these bodies are removed (if present) by the filter 24, which contains an adsorbent material, such as fullers earth, clay, and the like, and which serve to materially brighten and clarify the gasoline, thereby giving it the brilliant appearance so highly desired.

Likewise, the steps of my process, prior to filtering through the adsorbent material, insure a prolongation of the functions of the adsorbent material to an extent heretofore unknown, and in consequence the adsorbent material is easily reactivated by burning, or otherwise.

The nitrogenous bases and other basic impurities removed by the weak acid treatment collected in tank 39 may be recovered by a treatment such as is described in United tates Patent No. 1,686,136, it being especially noted that the strength of the weak acid employed is such as to convert the basic compounds into sulphates without material polymerization, or without reacting materially on acidicimpurities to change, or possibly destroy, such as are desired to be collected in the alkali treatment for recovery as products of value.

To this end, the strength of the acid may be varied Within rather large limits, depending on the chemical structure of the dis tillate treated, to obtain results and prod ucts unattainable in the use of strong acid in like quantities, in the same steps.

The acidic impurities removed by the caustic soda treatment and collected in tank 46 include such compounds as phenols, cresols, and the like, and/or naphthenic acids and the like which may be recovered in various ways.

The system of rotation employed is such that the gasoline is primarily contacted with a partially spent weak acid solution and finally contacted with a fresh weak acid solution, the final acid in any one period of rotation absorbing practically no impurities.

This is'necessary in my process, which is primarily for decolorizing the gasoline, because if even-a limited amount of impurities remain in the gasoline after the weak acid treatment, a stable color is not obtained, and such is one of the prime objects of my in vention; to producea gasoline havinga 30+ color on the Saybolt colorimeter, which color is stabilized.

In thus describing the treatment of a petroleum distillate, the exhausted acid collected in tank 39 and'the exhausted alkali in tank 46 may be withdrawn and shipped. to various places where the separation of metals from ores is accomplished by flotation.

Such flotation process, in general, depends on the fact that when ores are finely ground and added to water, the surface tension of which has been changed by the addition of a suitable material causing the formation of a froth when agitated, the metal particles will be held in the froth, while the silicious material and other impurities will sink.

The froth formation may be caused by passing water through a so-called flotation cell, and adding either the substantially exhausted acid, or substantially exhausted alkali, thereto in the right proportion to form a froth of proper consistency when agitated with a1r under pressure or otherwlse.

The finely divided ore is then added to the machine and the metal floats out with the froth and is recovered therefrom while the impurities pass out with the water, it being desirable that the froth does not persist beyond a vpredetermined period of time after leaving the flotation machine so that the metal values are more easily recoverable.

Thus, in a process of treating petroleum distillates, it will be seen that the acid and/or alkali will be used to substantial exhaustion and then withdrawn for use as frothing agents whereby no loss of acid or alkali occurs.

The exhausted acid referred to herein means an acidic liquor containing ten per cent (10%) or less H SO or equivalent acid, as uncombined acid, and the exhausted alkali refers to an alkaline liquor containing five per cent (5%) or less alkali, as uncombined alkali, but preferably both liquors are reduced to zero acidity and zero alkalinity.

I claim as my invention:

1. A process of decolorizing hydrocarbon material which comprises: passing distillate through a plurality of chambers containing dilute acid of about concentration and arranged in series relation, continuing the passage of distillate until the acid is reduced to approximately ten percent (10%) concentration in successive portions whereby the basic compounds are converted into sulphates without material polymerization, and removing the acid and reaction products as such successive portions.

2. A process of decolorizing hydrocarbon material which comprises: passing distillate through a plurality of chambers containing dilute acid of about 50% concentration and arranged in series relation, continuing the passage of distillate until the acid is reduced to approximately ten percent (10%) concentration in successive portions whereby the basic compounds are converted into sulphates Without material polymerization, and removing the acid and reaction products as such successive portions, while maintaining at least one of the chambers in operation.

3. A process of decolorizing hydrocarbon material which comprises: passing distillate through a plurality of chambers containingv dilute sulphuric acid of about 50% concentration and arranged in series relation, continuing the passage of distillate until the acid is reduced to approximately ten percent (10%) concentration in successive portions whereby the basic compounds are converted into sulphates without material polymerization, and removing the acid and reaction products as such successive portions.

4. A process of decolorizing hydrocarbon material which comprises: passing distillate through a series or" chambers containing dilute acid of about 50% concentration, whereby theacid is reduced to approximately ten percent (10%) concentration whereby the basic compounds are converted into sulphates without material polymerization and removed from successive chambers, then through an alkaline solution of greater than ten percent (10%) concentration, whereby the alkali is reduced to approximately five percent (5%) concentration.

In testimony whereof, I have hereunto set my hand at Long Beach, California, this 3d day of July, 1929.

SUMNER E. CAMPBELL. 

